New composite material based on micrographite particles in glassy matrices for applications in piezoresistive sensors

New composite piezoresistive material has been developed based on micrographite particles immersed in glassy matrix with composition containing several Pb-free oxides: Bi
2
O
3
, B
2
O
3
, SiO
2
, Al
2
O
3
and ZnO. This composition allowed to obtain reduced sintering temperature for the composite material thus avoiding loss of graphite during thermal processing in air. Methodology for producing piezoresistive films from pastes with micrographite particles includes the use of a sodium carboxymethyl cellulose (NaCMC) aqueous solutions during preparation of pastes. It was verified that NaCMC plays a decisive role in interactions between graphite particles and glassy matrix, providing good wettability of glassy matrix particles and homogeneous distribution of micrographite particles in the pastes. The films stability and piezoresistive characteristics of the films were verified in the mechanical tension experiments.